Readers discuss the handedness of DNA, celebrate the Explosives Act and reminisce about childhood experiments

Left handed might not be right

Rachel Brazil draws together many aspects of the biochemistry of Z-DNA in her feature article.

A commentary on the history of the putative left-handed form of DNA is also engaging. It is not universally accepted that the Z form is left handed. This handedness was deduced by Alexander Rich and his coworkers from fitting models they had built to their crystallographic diffraction patterns. It was not deduced from direct physical experimentation.

Many direct experimental results cast doubt upon that handedness. For example, several groups of crystallographers have reported that the right-handed B form, drawn into fibres, will transform itself into the Z form inside solid fibres. The mechanism and driving force necessary to effect a right-to-supposed-left helical transformation have never been explicit and have never been elaborated.

In other reported topological experiments conducted on closed circular two-stranded DNA specimens it has been possible to count the actual number of full helical turns using gel electrophoresis. The stretches of right-handed B-form DNA, taken with contiguous stretches of supposed left-handed Z DNA within the circle, have never resulted in the correct number of helical turns when added together.

Of course, these observations are separate and different from the ability of the Z form to generate anti-Z-DNA antibodies and to elicit specific identification from suitable proteins or sections of proteins. But Z-DNA is not necessarily left-handed.

Clive Delmonte FRSC
Via email

Colonel Majendie’s legacy

I was surprised by the contents of Michael Baldwin’s letter on fireworks. In the final paragraph he says ‘The pyrotechnics industry in the UK has withered to almost nothing, not helped by intrusive safety regulations.’

These ‘intrusive safety regulations’ had their origin in the Explosives Act 1875, which was brought about by the dedicated work of Colonel Vivian Dering Majendie, the government’s inspector of explosives. He was tasked in 1872 by parliament to investigate what was needed to improve explosives safety and later drafted the Explosives Act 1875 to regulate explosives. In the years since the Act the number of people killed or injured by explosives fell dramatically.

The 1875 Act defined a manufacturer as ‘any person who carries on any of the following processes, namely, the process of dividing into its component parts or otherwise breaking up or unmaking any explosive’. Taking apart explosive articles is especially hazardous. Explosives accidents were reported in the Explosives Inspectorate’s annual reports from 1876 to 1975. During the 19th and 20th century, the reports recorded incidents that involved children carrying out ‘experiments’ with fireworks and ‘ingredients from friendly pharmacists’. Some children were killed, others lost hands, were blinded, or were burnt.

In 1876, the first accident investigation was carried by Majendie. This involved two young men who decided to make some coloured fire compositions with ingredients obtained from a chemist shop. They took their manufactured compositions onto a pleasure boat carrying a works outing on the River Wensum in Norfolk. The compositions spontaneously ignited during the journey and resulted in the death of two young women and burns to other passengers.

So, please, stop criticising health and safety regulations such as the Explosives Act 1875 and later regulations as ‘intrusive safety regulations’. These carefully considered laws are designed to protect people, including children, from the hazards of explosives.

Michael Marriott FRSC
Norwich, UK

Licence to explore

I refer to the article ‘Hobby chemist guilty of possession of acids without a licence’.

I know given today’s world this is a difficult one but what a shame we have reached this point. I can still remember the joy as a small boy of my ‘chemistry set’ and the fun of going to the local chemist and buying interesting chemicals. It was this that led me to become a professional chemist.

If the young people of today are restricted from exploration and early science, is it any wonder that they turn away from the sciences?

John Williams CChem FRSC
Via email

20 years of Chemistry World

I have been a Chemistry World reader since the start 20 years ago and it provides me with up to the minute news from the world of chemistry – as the title reflects. In addition to the online access, I also receive a printed copy, so it is always in my bag for regular coffee shop visits.

Chemistry World has gone through a variety of changes and improvements over the years, which I feel have been well managed and sensible, covering both academic and industrial aspects and with scope to accommodate everyone from school children through college students, research workers and emeritus scholars. This is one of the reasons it continues to attract widespread, global attention. A magazine for everyone!

I have memories of the complaints that there was too much biology, and the content should be focused on chemistry alone. A misplaced argument that was rightly rejected at the time.

I also used articles from Chemistry World in teaching final year biochemistry graduate students and recall the enthusiasm for the well written and illustrated reports on a wide variety of current and relevant topics from academia and industry.

Keep it going, the past 20 years have been a big success and I hope to be reading for the next 20 years.

Anthony Corfield
Loughborough, UK 


We have three corrections for the March issue of Chemistry World.

The name of the author of the Last Retort article is correctly spelled Sim Bhaker (Chemistry World, March 2024, p64)

Acknowledgement should go to Talitha Humphrey for Classic Kit (Chemistry World, March 2024, p62), who tested Linnemann’s and other columns and began to exhume his story

We’ve made some changes to clarify the high entropy alloy article (Chemistry World, March 2024, p24) thanks to Mark Foreman’s kind intervention. You can read the updated version at

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